function imagelist($attach) { global $_G;
$attach['refcheck'] = (!$attach['remote'] && $_G['setting']['attachrefcheck']) || ($attach['remote'] && ($_G['setting']['ftp']['hideurl'] || ($attach['isimage'] && $_G['setting']['attachimgpost'] && strtolower(substr($_G['setting']['ftp']['attachurl'], 0, 3)) == 'ftp'))); 
$mobilethumburl = $attach['attachimg'] && $_G['setting']['showimages'] && (!$attach['price'] || $attach['payed']) && ($_G['group']['allowgetimage'] || $_G['uid'] == $attach['uid']) ? getforumimg($attach['aid'], 0, 200, 200, 'fixnone') : '' ;
$aidencode = packaids($attach); $is_archive = $_G['forum_thread']['is_archived'] ? "&fid=".$_G['fid']."&archiveid=".$_G[forum_thread][archiveid] : ''; }

size参数改大了之后你再在手机上看效果，缩略图是不是变大了？

看看，是不是我的网站缩略图还是原来那么大（200PX），但是清晰度怎么异常高呢？还有个小窍门，暂且让我保留一会儿，呵呵~

找到 static/image/mobile/style.css
修改这段样式中的红色字体

.plc .pi .message img,.plc .pi .img_one img { margin:0px 4px 0px 0; max-width:300px; max-height:300px; }